Coaxial switches and systems for microwave systems which may include those in which signal flow in unused paths is prevented by dimensioning for cutoff of waveguide mode



Aug. 2, 1966 s. A. RINKEL 3,264,581

COAXIAL SWITCHES AND SYSTEMS FOR MICROWAVE SYSTEMS WHICH MAY INCLUDE THOSE IN WHICH SIGNAL FLOW IN UNUSED PATHS IS PHEVENTED BY DIMENSIONING FOR CUTOFF OF WAVEGUIDE MODE Filed Dec. 3, 1963 2 Sheets-Sheet l 1 54/ 7 80 Q \u 4/ l x 90 -46 INVENTOR. SHE/MIA IV A. Rl/V/(El.

s. A. RINKEL 3,264,581 GOAXIAL SWITCHES AND SYSTEMS FOR MICROWAVE SYSTEMS WHICH MAY Aug. 2, 1966 INCLUDE THOSE IN WHICH SIGNAL FLOW IN UNUSED PATHS IS PREVENTED BY DIMENSIONING FOR CUTOFF OF WAVEGUIDE MODE 2 Sheets-Sheet 2 Filed Dec. 3, 196.3

INVENTOR.

SHERMAN A. R/N/(EL rm/was United States Patent COAXIAL SWITCHES AND SYSTEMS FOR MHCRO- WAVE SYSTEMS WHICH MAY 1N CLUDE THOSE IN WHICH SIGNAL FLOW IN UNUSED PATHS 1S PREVENTED BY DIMENSIONING FOR CUTOFF OF WAVEGUIDE MODE Sherman A. Rinkel, Bethpage, N.Y., assignor to General Microwave Corporation, a corporation of New York Filed Dec. 3, 1963, Ser. No. 327,707

' 17 Claims. (Cl. 333-7) This invention relates to coaxial switches and systems, and in particular to such switches for microwave radio frequencies.

In known microwave coaxial switches, their construction has been such that they have not been fully effective in suppressing signals through unselected transfer paths. For example, signal leakage on the order of 40- 70 db is characteristic of conventional RF coaxial switches. Moreover, it has been found that undesirable impedance mismatches occur after the switching operations that result in spurious reflected signals in the standby circuits. Multi-position coaxial switches generally employ rotary mechanisms that are stepped through successive intervening positions to a selected one, rather than moved directly thereto, so that the selection time includes that of rotating the switch pole through all intervening positions.

It is therefore among the objects of this invention to provide a new and improved coaxial microwave switch.

Another object of this invention is to provide a new and improved coaxial microwave switch capable of suppressing or attenuating the signal being propagated by about 100 db or more in the unselected transfer path or paths.

Another object of this invention is to provide a new and improved programmable coaxial switching system for selectively switching different combinations of transfer paths into a circuit.

Another object of this invention is to provide a new and improved programmable coaxial attenuator for selectively switching different attenuations into a circuit over a broad range and with high accuracy.

Another object of the present invention is to provide a new and improved coaxial microwave switch which is effective to ensure impedance matches to the various transfer paths under operating conditions.

In one embodiment of this invention, a metallic housing is provided having one or more passages, in each of which a rod reciprocates. Each rod has at least one conductive portion which engages different combinations of contacts when the rod is moved from one position to another. The wall of each passage surrounding the conductive portion of the rod forms a coaxial shield to provide a coaxial connection between the contacts in engagement therewith. The wall of the passages surrounding non-conductive portions of the rod functions as a waveguide beyond cut-off with respect to the wavelengths of the signals being switched to ensure a high attenuation of signals and essentially block transmission thereof to contacts not connected to the conductive portions.

In accordance with a feature of this invention, a plurality of such passages are provided and various circuits are provided in other passages within the housing and connected to certain ones of the contacts. Thereby, the switch may be operated selectively connecting these circuits between input and output terminals. In accordance with another feature, different electrical circuits are connected in the other passages, and the switch is effective to connect a selected one of said circuits between input and output terminals.

In accordance with another feature of this invention, the coaxial switch r-od has a plurality of conductive por- 3,264,581 Patented August 2, 1966 "ice tions, and different combinations of contacts are connected to the conductive portions in different operating positions of the switch rod.

In accordance with another feature of this invention, a coaxial switch of the type described is connected in a system in which at least one signal source is connected to a switch terminal and at least one load circuit is connected to another switch terminal. In all operating positions of the switch, both the source and load circuit are connected through the switch to their respective characteristic terminating impedances.

In accordance with another feature of this invention, a system of coaxial switches of the type described is provided in which the switches are connected in cascade with the output terminal of one being connected to the input terminal of the next and so on. In this fashion, a signal source connected to the input terminal of the first switch may be connected to any one of a plurality of the output terminals of the second such switch, and so on, in one embodiment of the invention. In another embodiment of the invention, employing a plurality of passages in each switch, different combinations of circuit elements within the switches are connected in series by selective, combinatorial operation of the switching rods.

The foregoing and other objects of this invention, the features thereof as well as the invention itself, may be more fully understood from the following description when read together with the accompanying drawing, in which:

FIG. 1 is a partially sectional view in front elevation of a coaxial switch and attenuator system embodying this invention taken on a vertical plane through the center thereof and along the line 11 of FIG. 2;

FIG. 2 is a sectional view along the line 22 of FIG. 1;

FIG. 3 is an enlarged fragmentary sectional view of a sliding contact portion and is taken along the line 3-3 of FIG. 1;

FIG. 4 is a schematic representation and circuit diagram of a plurality of the coaxial switches and attenuators of FIG. 1 connected in cascade and in a circuit;

FIG. 5 is a schematic representation and circuit diagram of another coaxial microwave switch and circuit embodying this invention;

FIGS. 6A and 6B are schematic representations and circuit diagrams under different switch-operating conditions of another form of this invention; and

FIGS. 7A and 7B are schematic representations and circuit diagrams under different switch operating conditions of still another form of this invention.

In the drawing, corresponding parts are referenced throughout by similar numerals.

In FIGS. 1 to 3, a coaxial switch and attenuator unit 10 comprises a metallic (e.g. aluminum) housing 12 consisting of two mating metal sections 14 and 16 which are removably fastened together in a suitable fashion, for example, by means of bolts 18. Dowel pins 20 are provided in diagonal corners of one of the sections it to mate with corresponding holes in the other section 14 to ensure proper mating relationship of the two sections.

Each of the sections 14 and 16 is similarly formed and provided with a pair of semi-cylindrical countersunk passages 22. The latter extend from the outer opposite sides of each section to a second pair of semi-cylindrical passages 24-, respectively, and the latter are at right angles to the former and extend for most of the length of the housing section. Two other semi-cylindrical passages 26 and 28 are formed between the passages 24 adjacent to opposite ends thereof. In addition, an enlarged rectangular recess or passage 30 is provided at the lower ends of the passages 24 and communicates therewith, within which certain parts move as is described hereinand concentrically spaced tubular inner conductors 37 and 3-9 fixed therein. The connectors 32 .and 34 are inserted in the outer ends of the passage 22 and fastened to the opposite sides of the housing 12.. The outer shields of the connectors 32 and '34 make electrical connection. with-the housing 12, and the inner conductors 37 and.

3-9of those connectors 32 and 34 make electrical connection at their ends with rods 36"and 38, respectively,

which extend along the axes of the passages 22. Di-' electricbeads 40-surround the rods 36 and 38 within the passages 22 to insulate the rods from the surround 1' ing conductive housing. The rods=36 and 38 are identical and are (fastened in position by means of suitable .non conductive pins 42 extending therethrough into the ad-' jafcent housing Wall.

The inner ends of the rods 36 and 38 are enlarged and bifurcated (as shown in FIG. 3). The bifurcated ends 44 and 56function as sliding resilient contacts and en-v gage respective conductive sections 46 and 58'on rods *48 and 60. These rods are coaxially and reciprocatinglymounted within the passages 24.

' The rods 48 and 60 function as switching elements and ina preferred form are fabricatedof dielectric material, such: as polystyrene, nylon .or a suitable plastic, with.

conductivecoatings formed around-the central portions thereof to form the conductive sections 46. and 58. Sections 50 and 1 on either end of the rod 48 and sections 52 and'53on rod 60 function asnon-conductive or insulating sections of the switching rods. These rods are coaxially centered within the cylindrical passages formed.

bythe mating semi-cylindrical passages 24 by means of suitable insulating spacer beads 54 at each end of the passages 24.'

The switching rods 48 and 60 are each preferably made "of a solid dielectric material such as polystyrene or:nylon,

and the conductive portions 46 and 58 are metallic sur- [faces formed, for example, by a conductive film of silver "deposited in a recess around the central periphery of the rods. Thereby, a substantially continuous outer surface with the remainder of the switching rod is provided to ensure a smooth transitional surface as the rods move within the contacts 44 and 56.

The insulating beads and sleeves 40 and 54 are pref erahly annular beads which may be made. of Teflon or similar material that has a low electrical loss and provides a good bearing surface.

The lower ends of the switching rods 48 and 60 are fixedly connected to opposite ends of a yoke or crossmember 62.. The yoke 62 moves up and down within the reotangular recess-St) in the housing 12 and thereby actuatesin unison the rods 48 and 60. Fixed to the midpoint of the yoke 62 is a driving armature shaft 64 which passes through a bushing 66 fitted in a cylindrical.

passageway in the lower end of the housing sections 14 upward position by a suitable biasing spring .69 when the solenoid is deenergized.

A guide rod 70' has its upper and lower ends fixed Within the housing section 16 onopposite sides of passage 30, and it passes through an aperture in yoke 62. This rod prevents rotation of yoke 62 about the .axis of shaft 64 during its upward and, downward movement. Theyoke .62.is provided with an adjustable set screw 72 which impinges upon the lowerwall of'recess 30 and a screw 74 which may be adjustable and which impinges upon the upper wall thereof; both screws function as limit stops. Thereby, the switching rods 48 and 60 are and 16. The shaft 64, in turn, is actuated downward.

by the selective energization of a solenoid 67 by a suitablecontrol current [from a source-68 and is restored to an properly positioned with respect, to the: contacts? 44 and 56 (and also with respect. to certainyother; contacts) in a each of their two extreme positions.

In the .form of the invention shown in FIG. 1, two electrical paths are provided within the. passages26 :and

28.? These paths; may have any desired'electrical char- 1 In the. form-of the invention shown ;in FIG.

acteristics. 1, the path within passage26 comprisesv a 'T-pad although it should be understood that many other types of 6 electrical circuits such as: pi-networks, etc. may alternatively be employed therein.-

Within passage 26, the T-pad consists of a tubular con- 7 ductive member having its outer surface in conductive contact with the passage wall. Member 80 is formed of two threaded parts one threaded .within' theqother (as shown by the zig-zag lines; in the sectional view of FIG.

'7) which parts form spaced shoulders to retain the edge of a disc resistor 82 centrally and-internally between them.

of the: dis-c 82 Ion opposite sides thereof, andthe outer ends are. fastened 'condnctivelyl to bifurcated contacts 88 and 90, respectively; These contacts 88 .90 are similar. in construction to contact 44 andare fixed within member '80. by suitable insu lating ;pins. .When thepswitchi-rods 48; and 60 are in the lower position shown in 'FIG. 1, z

the contacts 88. and 90 :engage. the non-conductive ,sec- 'tions 50 and 52, and in the upper position, theconductive surfaces 46 and 58',irespectively; The T-pad thusconsists of the two series resistors 84 and 86 connected in circuit with, their junction connectedto .ground (the. a

metallic housing) via the discres-istor 82.

There is also provideda second electrical path within the passage 28,;which includes a dielectric .sleeve 92 through which aconductive' rod 94 extends.

ductive rod 94' is enlarged at each endandbifurcated to formcontacts 96 and 98 which generally are .similar' to 'contacty44. These contacts 396 and98- engage the conductive surfaces 46 and 58 when the yoke-62 is'in its lower extreme position as shown in:FIG.1 1,.zandthe nonconductive sections 51 and 53 in;its'upper position.

When the yoke 62 is in its lowest position (as: shown in FIG. 1), signals coming .into coaxialv connector 32"pass r via contact 44, conductivesection 46 of the switchingrod 48, contact .96, red 94,- contact 98*, conductive section 58,

contact 56, and outethrough connector'34.- Thereby,,a

straight-through connection is made, and. the housing Walls of the cylindrical passages providecoax-ial shields for the inner conductors between the connectors 32 and 34.

With the yoke in the upper position, incoming signals coaxial-connectors 32 and 34. r:

Regardless of which electrical .path is selected, leakage "of the signal through;the other path is attenuated byap- This'. is accomplished by providing that: the. conductive ,walls of the passages sur-. rounding the non-conductive portion :of the. rods 48-and proximately 100 db or more.

60. have dimensions which make them=waveguides beyond cutofi With respect to the applied signal Efrequencies. Thus, when the; yoke 62 iisi in the position shown in FIG. 1, the walls of the passage '24 surroundingthe non-conductive portion 50 betWeen contacts 44 and 88: have a length which I is more than three; times the diameter of V the passage; 241.v For a distance alongthis section of, the.

wall equal-to the diameter, there is approximately-a 32 db. attenuation at the bandof frequencies applied. The presence of the dielectric rod 50 this region etfec iv' y Two rodresistors 84and 86 are fixed axially 'within member :80 !and %spaced therefrom. The inner. ends of .the rods 84 and 86 conductively engage the center- The conlowers the cutoff wavelength, and the diameter of the surrounding passage wall is actually made somewhat smaller to ensure a cutoff characteristic. When the yoke 62 is moved to the uppermost position, the wall of the passage 24 surrounding the dielectric rod 51 between the contacts 44 and 96 similarly constitutes a waveguide beyond cutoff.

Thus, with respect to the unselected path, the leakage is attenuated 100 db or more in each of the two sections of waveguide beyond cutoff. This leakage signal of 100 db is but one practical value, and it may be made as large. as desired by simply lengthening the cutoff tubes. Practical limitations exist due to other leakage paths; e.g. currents may flow at the junction of the two halves of the housing, and connector leakage may exist. Practically, for a desired T-pad attenuation of 100 db, the leakage path attenuation should exceed this by at least 20 db, and preferably 30 db to eliminate significant errors in the attenuation of the desired path. With a leakage path attenuation equal to the desired attenuation, extremely large errors may result; this condition is avoided in practice by a suitable choice of parameters so that the leakage path attenuation is sufficiently larger than the desired attenuation.

Any desired circuits of different characteristics may be placed in the transfer passages 26 and 28. For example, filter circuits, diode mixers,'limiters or clippers may be used. Moreover, both transfer passages may have different circuits other than a straight-through path.

FIG. 4 shows two of the coaxial switches of FIG. 1 connected in cascade. They may be used, for example, as two-position switches in a binary configuration. In this case the electrical paths of the switches are furnished with attenuators such as T-pads constructed to introduce binary values of attenuation, i.e., 1, 2, 4, 8, for successive stages. By appropriate combinatorial selection of the fixed attenuations, any desired attenuation value can be connected in circuit in a single switching operation for each stage and with all of the operations occurring at the same time. Thereby, a high-speed, programmable system is provided for selecting any desired value of attenuation (or other electrical characteristic). 7

In FIG. 4, as in the rest of the figures to follow, the novel switches described above are shown schematically. Parts representing those described in FIG. 1 are referenced by similar numerals. Pairs of vertical lines represent the conductive walls of the passages 24 depicted in FIG. 1, and the horizontal line pairs represent other related conductive passage walls or shields. The resistors schematically indicated within those pairs of lines represent the non-conductive portions 50, 51, 52 and 53 of the switching rods (and in each case represent a Waveguide beyond cutoff), and the lines 46 and 58 represent the corresponding conductive sections of the switching rods. The resistors 82, 8 4, 86 represent the T-pad in the first conductive path, and the arrowheads represent the contact members which engage the conductive and non-conductive sections of theswitching rods. Other parts of the apparatus 10 are also numbered to correspond to their counterparts inFIG. 1.

A source 110 is connected to the input connector 32 of a first switch 10, and a :matched or characteristic load impedance, illustrated schematically as the resistor 120, is connected to the output connector 34 of a second switch 10', corresponding parts of which are referenced by similar numerals with the addition of a prime The switches 10 and 10 may be constructed in separate housings or they may be formed in the same housing. In the latter case, the coaxial coupling 111 between the output of one and the input of the other may be formed in another passage in the housing similarly as with the coupling 94. The corresponding parts of the two switches 10. and 10' are the same in construction, except for the resistors in the T-pad. The T-pad resistors 99, 100, and 101 are chosen to have a different attenuation characteristic from the switch 10 T-pad. For example, the T-pad in switch 10 may introduce a one db attenuation, and the T-pad in switch 10 may introduce two db or any other selected attenuation. If one db attenuation is desired, switch 10 is actuated to the attenuating path by its solenoid 67, whereas switch 10' is in the nonattenuating position. If two db attenuation is desired, the positions of the rods in switches 10 and 10 are reversed; and if three db attenuation is desired, both are actuated to the attenuating position. Any desired additional number of such switches having successive binary or other characteristics may be similarly disposed in the same housing or separately to achieve any desired attenuation characteristics. The invention is not limited in its application to the use of attenuators in one or both of the two transfer paths of each switch. Other circuits may be employed to achieve desired combinations of characteristics.

In the switches of both FIGS. 1 and 4, the source 110 and load 120 are connected in circuit in all positions of the switches so that both are terminated in their characteristic impedances in all switch positions.

Another coaxial microwave switch and circuit embodying this invention is shown in FIG. 5. Here the switch is constructed so that the switching rods can be separately moved, and rods may be used that have more than one conductive section. FIG. 5 is an example of such a device used as a single pole-four throw switch having three rods generally indicated by the numerical designations 102, 103, and 10 4; 103 and 104 are coupled so asto move in unison, and may be formed as a single rod with the conductive surfaces properly located. There are also two signal paths 105 and 106 which contain straight-through conductors. The source 110 applies an input signal via input coaxial connector 32 to the rod 102. Four output coaxial connectors 112, 113, 114, and are also connected to contacts constructed to engage the rods 103 and 104 as shown.

The solenoids 67" and 67" determine the upward or downward positions of the rods 102 and 103, respectively. In the positions of the rods shown, the source 110 is connected via the conductive portion of rod 102, the lower signal path 106, and the conductive portion of rod 104 to output terminal 118, to which a matched load is connected. If solenoid 67" is energized so as to pull rods 103 and 104 down, the source 110 is then coupled to terminal 119. If rod 102 is up and rods 103 and 104 are also up in the position illustrated, the source 110 becomes coupled to the terminal 116- via. the conductive portion of rod 102, the upper signal path and the conductive portion of the rod 103. If, while rod 102 is in the up position, rods 103' and 104 are down, source 110 is cou pled to output terminal 117. In all positions, as explained above, the Walls of the passages around the noncond-uctive portion of the rods .102, 1 03, and 104 between the input contact and the contact for the unselected path are dimensioned to function effectively as waveguides beyond cutoff at the band of frequencies supplied. The details of construction of this switch will be readily apparent from the foregoing description.

Another form of the present invention is shown schematically in FIGS. 6A and 6B which represent two different switching positions of the same switch. In this embodiment, there is a source 110 coupled to an input connector 111 as in the previous example, but within the single passage there is disposed a rod 121 having two conductive sections 122 and 123 spaced from one another by an intermediate non-conductive section. There are four output contacts represented by the arrows pointing toward the left and four output connectors 124, 125, 126 and 127. The output at connectors 124 is connected to a characteristic impedance element 128 which provides a proper termination for signals from the load connected to output connector 125. Similarly, the characteristic impedance element 129 coupled to connector 127 provides a proper termination to the load 131. In the nector 125 to load 130. At the same time, the conductive portion 123.connects the unselected load 13-1 to the terminating impedance 129. In FIG. 6B, the rod 121, has

been elevated to its uppermost position so that the source 110' is now connected via the conductor 123 to the load 3 131 whereas load 130is connected to its terminating im-.

pedance 128. Thus, in either position of the switching rod, the source is connected to a characteristic load imacteristic terminating intpedances. Thereby, reflections due to mismatches are avoided all positions of the.

switch. The switching rods 102, .103, and 104 of FIG. 5

may be constructed similarly to those of FIGS. 6A and 6B to have pairs of conductive sections and additional contacts therefor; thereby, loads at the output terminals i may be properly terminated in all switchpositions. As in the previous examples, the portion of the passage walls surrounding the non-conductive part of therod between the input contact and the contact :for the unselected path is dimensioned to constitute eifectively a waveguide beyond cutoff.

Another form of the invention is shown in FIGS. 7A

and 7B which schematically represents a switch construction that may be used as a transfer switch'of the. type employed in antenna applications. This switch 10" is similar to the switch 10 of.FIG..1 except that the two electrical signal paths employ inner conductors 94 and 94 which are essentially non'resistive at the band of frequencies involved. There are also twov switching rods 121 and 121 which may be substantially identical to that of FIGS. 6A and 6B. The switching rods are actuated...

in unison by a yoke 62; There are two input connectors 111 and111'. coupled to terminals 132. and 5133- 132 and 13 3 are effectively isolated from the othersand V are connected together, as are the terminals 136 and 137. Thus, sources or loads connected to the various terminals are properly terminated in both positions ofthe switch. I

The switch construction of FIG. 1 is generally applicable to eachof the other switch arrangements described.

above, withthe modifications required in each instance.

The straight switching rod construction that is illustrated is generally preferred. However, the invention is not limited thereto and may also be constructed with gen-,

erally annular rods that reciprocatingly turn in annular passages formed in a metalhousing. Switching contacts would engage the rodsatapp-ropriately spaced points in.

n-throw switch. Of course, any desired number of rods.

having any desired number of conductive portions may be usedwith any. appropriate number of contacts to provide other switching devices, patterns, and circuits. The electrical paths may'have any desired circuitry or other electrical characteristics. The movement ofthe rods may be accomplished by electro-magnetic means as shown,: by

manual means, by hydraulic actuation, etc.

Furtheri more, either the rods themselves may be moved or the housing may be moved, or both. As many such arrangements of applications will occur to those skilled in the.

areupon penusing the specification and drawings herein and these applications do not depart fromthe essence I of the invention, this invention should be limited solely by the claims which follow.

What is claimed is:

1. A coaxial microwave :switchifor use with a source of signals within a certain frequency band, said 'switch comprising: means forming first and second passages each having conductive walls,,first and second rods respectively movably mounted within said first and second :passages, each of said rods having at. least one conductive. section, first andsecond contacts respectively engaging the .con-.

H ductive sections of saidfirst-and secondrods, aplurality '10 pedance, and the loads are themselves connected to charof, electrical paths each having means for contacting said conductive vsectionsrin selected operating positions ofv said rods,'and means for reciprocating said rods in unison'to connect said electrical paths between saidcontacts, the.

walls of said passages surrounding saidqconductive. sectionsproviding coaxial shields therefor and=the wallsof said passages not surrounding saidfconductive sections being dimensioned to functionaswaveguides beyond cutoff with respect tosaid-band of frequencies; 5.

2. A coaxial microwave switch as recited in claim 1 wherein said trod reciprocating means is. effective to con nect one or another of saidelectrical paths between saidcontacts. V

3. -A coaxial microwave switch :as recited in, claim 2 wherein said electrical paths have different electrical char-' .acteristics.

4. .A coaxlal microwave switch asrecited in claini'3 and further .comprising a secondswitchof substantially siln ilar construction as the :first switch, the second contact ofone. of said-switches being connected to. theiirstcontact of another thereofi 5.-A coaxial=microwave switch as recited-in claim l said second contacts-together;

6,1.A coaxial switch for use with ;a source. ,of signals within a certain frequency band, saidiswitchcomprising: a conductive .housing, first andsecond substantially] parallel passages therein, :third and fourth passages therein whichiaresubstantially parallel to one another andflocated between and ztransverse to said first andtsecond passages; and communicate. "therewith, first and second .rods respectively, movably mountedwithin :said. first and second passages, .eachof said rods having a .conduc. I tive surface, section'disposed between non-conductive sur- 1 face sections, -fifth and sixth passages communicating with said first and second passages.respectivelyendextending to the outside: of said housing, input means for connection to a coaxial line, said inputtmeanstbeing disposed within said fifth :passageand including :an input contact for engaging theiconductive section of said .first rod, output means disposed within said sixth passage for connection :to a coaxial line and including'an output con-.

tact for engagingtheiconductive section v;of 1 said second rod, a firstzelectrical path disposed insaid third passage, said path including .two contacts: for: engaging said ,first and second rods, respectively, aiisecond electricalz path disposed. in said. fourth passage and including "two con, tacts forengaging saidfir'stand second rods, respectively, said ielectrical'paths having different? electrical characteristics, and means for reciprocating said rods-in unison-into first and second operating positions, said first electrical path being, in said first: position, connectedvia said conductive sections between said input :and said'out' put means, said second electricalpath being, :insaid second position, connectedvia said conductive sections, ,between said input and output-means,:the walls of said passages surrounding said iconductive surface sections.

providingcoaxial shields therefor, and the wall ,of said passages surrounding said non-conductive :surface seetionsrbetween said.inputcontact-andqthe, .contact of the path not selected being dimensionedto function as wavewherein said second electrical path has essentially no attenuation.

8. The coaxial switch according to claim 7 wherein said means for reciprocating said rods includes a rigid yoke coupled to said rods and a shaft connected to said yoke and extending from the interior of said housing to the exterior thereof for actuation.

9. A switching system for microwave signals, said system comprising: a source of microwave signals within a certain frequency band; a plurality of coaxial microwave switches in series, each of which includes: first and second passages. each having conductive walls, first and second rods respectively movably mounted within said first and second passages, each of said rods having at least one conductive section disposed between non-conductive sections, an input means having an input contact for engaging at least one of said conductive sections of said first rod, an output means having an output contact for engaging at least one of said conductive sections of said second rod, a plurality of electrical paths each having means for contacting conductive sections of both rods, each path having selected electrical characteristics, and means for moving said rods in unison into selected operating positions thereby to connect selected ones of said electrical paths between said input and output contacts, said switches being coupled so that the input means of the first of said switches is connected to said source and the input means of subsequent switches are respectively coupled to the output means of the preceding switch, the output means of the last switch being connected to a load circuit, said switches being arranged so that upon operation of selected ones of said moving means, predetermined combinations of said electrical paths are connected in a series circuit between said source and said load, the walls of the passages surrounding the conductive sections of each switch providing coaxial shields therefor, and the walls of said passages surrounding said non-conductive sections being dimensioned to function as waveguides beyond cutoff to signals within said frequency band.

10. The switching system according to claim 9 wherein each switch has two paths, wherein one path in each switch has substantially zero attenuation and wherein all the second paths in said switches have substantial attenuation characteristics which are binary-related to one another.

11. A coaxial microwave switch for use with signals within a certain frequency band, said switch comprising: first and second passages each having conductive walls, a first rod means disposed within said first passage, a second rod means disposed in said second passage, all of said rod means being movably mounted within their respective passages, said first rod means having at least one conductive section and said second rod means having a plurality of conductive sections disposed between non-conductive sections, input means communicating with said first passage and including an input contact which engages a conductive section of said first rod means, a plurality of output means communicating with said second passage, each of said output means including an output contact for engaging a different one of the conductive sections of said second rod means, a plurality of electrical paths each having a contact which engages said.

12. The switch according to claim 11 whereinsaid paths have substantially no attenuation at said signal frequencies.

13. The switch according to claim 11 wherein said means for reciprocating said rods are constructed so. that said first rod may be moved independently of the other rods.

14. A coaxial microwave switch for use with a source of signals having frequencies within a certain. frequency band, said switch comprising: at least one passage having a conductive wall, at least one rod mounted for axial movement within said passage, each rod having a plurality of spaced conductive sections separated from one another by a non-conductive section, at least one input means for connection to said source, said input means including a contact for engaging at least one of said conductive sections, a plurality of output means for connection to a plurality of load circuits, each of said output means including an output contact engaging said rod, and means for moving said rod into predetermined operating positions thereby connecting said input means via. at least one of said conductive sections to selected ones of said output means, the walls of said passage surrounding each of said conductive sections providing a coaxial shield therefor and the walls of said passage surrounding said non-conductive sections being dimensioned to function as a wave-guide beyond cutolf with respect to signals within said certain band.

15. A coaxial microwave switch system including: a source of signals having frequencies within a certain frequency band, a load circuit, said source and load circuit having a certain characteristic impedance, and a coaxial microwave switch comprising: at least one passage having a conductive wall, at least one rod mounted for axial movement within said passage and having at least one conductive section, at least one input means connected to said source and including an input contact which engages said rod, at least one output means having an output contact which engages the conductive section of said rod, said output means being connected to said load circuit, and means for connecting said source and said load via said conductive section and via different circuit paths to characteristic terminating impedances in all of the operating positions of said switch, said connecting means including means for reciprocating said rod between predetermined operating positions, the walls of said passage providing a coaxial shield for said conductive rod section and being dimensioned to provide a waveguide beyond cutoff with respect to signals within said certain band.

16. A coaxial microwave system comprising: a source of signals having frequencies within a certain frequency band, a microwave switch which comprises at least one passage having a conductive wall, at least one rod mounted for axial movement within said passage, each rod having a plurality of spaced conductive sections separated from one another by a non-conductive section, at least one input means connected to said source, said input means including a contact for engaging at least one of said conductive sections, means for reciprocating said rod in said passage in a plurality of operating positions, a plurality of output means each of which includes an output contact for engaging said rod; a plurality of load circuits connected to selected ones of said output means, a plurality of impedance elements connected to selected others of said output means, each element having the characteristic terminating impedance value for a different one of said load circuits, said load circuits and said characteristic impedance elements being arranged so that in a first of said operating positions a first of said load circuits is connected to said source through a first of said conductive sections while a second of said load circuits is connected to its characteristic terminating impedance element through a second of said conductive sections whereas in a second of said operating positions said first load to 11 t circuit is connected to its characteristic terminating impedance element through said first conductive section while said second load is connected to said source through said second conductive section, the wallsof said passage surrounding each of said conductive sections constituting a coaxial shield therefor and the walls of said passage notv surrounding said conductive sections being dimen-:

sioned to function as a waveguide beyond cutofi with respect to signals within said certain band.

175A coaxial microwave switching system comprising: a source of microwave signals having frequencies within a certain frequency band; a microwave switch having at least one passage having a conductivewall, at least one rod mounted for axial movement within said passage, each rod having at least spaced first and second conductive sections, at least one input means connected to said source and including an input contact for engaging said conductive sections, means for reciprocating said rod into first and second positions andfirst, second, third, and, fourth output means having respective output contacts forengaging said rod; first and second load circuits respectively connected to said output contacts of said-first and I second output means; and first and second impedance means respectively .coupled tothe contacts of-said third 3 and said fourth output means, said. first and second impedauce means respectivelyhavingyalues equal to the characteristic terminating impedances of said first and second load circuits, said first load being connected, via said firstconductive section, to said source in said first position and to saidfirst impedance: means in saidsecond position, said second load beingconnected, via said secondsection, to said second impedanceymeans in said' first position and to saidsource in;said second position,: the, wall of said passage providing a coaxial shield for 9 said conductive rod sections and being dimensioned to, provide a Waveguide beyond-cutoff with respect to signals within said certain band.

References Cited by the Examiner UNITED STATES PATENTS- 3,087,125 4/1963 Scholefield 333-7 HERMAN KARL SAALBACH,{Primary Examiner.

R; D; 2COHN, Assistant Examiner.

8/1960 Holzschuh et a1 3337 

1. A COAXIAL MICROWAVE SWITCH FOR USE WITH A SOURCE OF SIGNALS WITHIN A CERTAIN FREQUENCY BAND, SAID SWITCH COMPRISING: MEANS FORMING FIRST AND SECOND PASSAGES EACH HAVING CONDUCTIVE WALLS, FIRST AND SECOND RODS RESPECTIVELY MOVABLE MOUNTED WITHIN SAID FIRST AND SECOND PASSAGES, EACH OF SAID RODS HAVING AT LEAST ONE CONDUCTIVE SECTION, FIRST AND SECOND CONTACTS RESPECTIVELY ENGAGING THE CONDUCTIVE SECTIONS OF SAID FIRST AND SECOND RODS, A PLURALITY OF ELECTRICAL PATHS EACH HAVING MEANS FOR CONTACTING SAID CONDUCTIVE SECTIONS IN SELECTED OPERATING POSITIONS OF SAID RODS, AND MEANS FOR RECIPROCATING SAID RODS IN UNISON TO CONNECT SAID ELECTRICAL PATHS BETWEEN SAID CONTACTS, THE WALLS OF SAID PASSAGES SURROUNDING SAID CONDUCTIVE SECTIONS PROVIDING COAXIAL SHIELDS THEREOF AND THE WALLS OF SAID PASSAGES NOT SURROUNDING SAID CONDUCTIVE SECTIONS BEING DIMENSIONED TO FUNCTION AS WAVEGUIDES BEYOND CUTOFF WITH RESPECT TO SAID BAND OF FREQUENCIES. 